1. Field of the Invention
The present invention relates to a dental implant system, and in particular to an improved dental implant system which is capable of enhancing a strength of a dental implant by improving an assembling structure of an implant root planted in an alveolar bone, an abutment assembled to the implant root and a crown covering the surface of the abutment, and implementing an easier dental operation, so that it is possible to increase a selectable range of operation based on the condition of patient's teeth.
2. Description of Related Art
In the dental implant system, an implant root is inserted into an alveolar bone and is combined to a bone. Thereafter, an abutment adapted to support the implant is engaged to the implant root. A crown is covered onto the abutment. According to the above implant system, it is possible to independently plant one tooth. In addition, since the thusly planted implant has a certain supporting force, it is unnecessary to cut a natural tooth due to the damaged tooth or drawn-out tooth. In other cases, it is possible to stably support a denture. In addition, the life span of the same is long, and a physical appearance of the teeth is good. There are many advantages.
In detail, the implant may be classified into a screw type and a non-screw type.
FIG. 1 is a view illustrating a screw type system which is first introduced and is most widely used and has the U.S. Pat. Nos. 4,330,891, 4,763,788, 4,824,372, 5,064,375, 5,064,425, 5,069,622, 5,080,589, 5,098,293, 5,125,841, 5,145,371, 5,154,612, and 5,269,685.
As shown therein, the screw type implant includes an implant root I which has a self-tapped screw I1 in an outer circumference of the same and is inserted into and combined with an alveolar bone S, an abutment A which is fixed to the implant root I by an abutment screw A1 screwed to an inner circumference of the same, and a crown engagement member E which is engaged to the abutment A by a fixing screw A2 of the crown.
Here, reference character A0 represents an auxiliary screw which seals a screw hole of the implant root I until the implant root I is combined with the alveolar bone S and helps a bone combination of the implant root in the alveolar bone and prevents an insertion of a debris of food. A dotted line represents a crown C processed and installed, after the alveolar bone and the operated portions are healed up.
The above screw type implant system needs lots of parts, so that the fabrication and maintenance costs are expensive, and an operation is complicated. Therefore, a complication may be developed. In addition, the medical care insurance rate of the patient may be increased.
In particular, the above system is implemented based on an engaging force of the screws A1 and A2 between the parts, the maximum external force such as a uniting force, etc. is determined based on the size of the width of the screw thread and the width and length of the implant. Therefore, the supporting force is small. In case that the supporting force is not bearable, the screws may be loosened.
In addition, the dental implant system in the screw type may be resistant to the compressing force when a uniting function is performed in the mouth. However, when the tension force is increased, the screws may be loosened during the use of the implant.
In addition, a certain gap between the implant root and abutment is formed by a poor interconnection between the implant root and abutment, whereby a certain bacteria may invade thereto to cause a sanitation problem and an inflammation in a surrounding tissue, so that an alveolar bone may be absorbed.
FIG. 2 is a view illustrating the dental implant system of the non-screw type which is invented to overcome the problems of the screw type implant system. As shown therein, there is provided a locking taper method which is implemented based on a surface friction force with respect to the engagement between parts.
The constitution of FIG. 2 is a representative in the locking taper method which is commercially available of “Bicon”.
In the constitution of the above system, a well I2 having the tapered surfaces which are expanded in an upper direction is formed in the interior of the implant I inserted into the alveolar bone S, and a post portion A3 having a certain taper corresponding thereto is extended in a lower portion of the abutment A. Namely, the abutment A is engaged to the implant I based on a surface friction force between the well I2 and the post portion A3.
An expanding flare portion A4 is provided in an upper portion of the abutment A, and both sides of the same are cut into provide a conical head forming a slanted surface A5.
In the above conventional dental implant system, the engaging operation with respect to the alveolar bone S is implemented by the dental implant system I, and the abutment A supporting the crown C is engaged to the implant root I.
However, since an external force such as a uniting force is applied to the abutment A through the crown C, the strength of the above system is determined based an engaging force between the abutment A and implant root I and the strength of the implant root I itself.
When compared with the screw type of FIG. 1 in which the engagement is implemented based on the screw treads of screws A1 and A2 which have relatively smaller diameters, the locking taper method of FIG. 2 has much higher engaging forces, and it has a screw loosening problem. However, since the maximum strength is determined based on the minimum diameter of the engaging part, there is a big problem in that point.
Namely, when assembling the implant root I to the abutment A, the post portion A3 of the abutment A is inserted into the well I2 formed in the center of the implant root I. Therefore, the size “a” of the neck portion of the post portion A3 and the size “b” of the surrounding portion of the implant root I which size is obtained by subtracting the size of the neck portion are too small as shown in FIG. 3.
Therefore, a breaking problem may occur in case of the teeth requiring a larger uniting force such as back tooth,. The above problem may be most critical to the conventional implant system. So, it is most needed to overcome the above problem.
In particular, after being implanted, the minimum diameter of the surrounding cave of the implant is preferably about 2.0 mm. Therefore, in case of the constitution in FIG. 2, the minimum diameter should be 7.5 mm. The relatively small portion needs a small implant. The size of the neck portion of the post portion of FIG. 2 should be over 2.0 mm not to be easily broken. In the above conventional method, the actual use of the implant is limited due to the impossibility to decrease the size of the implant, In addition, if the size of the implant is much smaller, the implant may be easily broken. Therefore, there are many problems for actually using the same.
In the conventional implant of FIGS. 1 trough 3, the upper portion and lower portion of the implant root may not be formed at a certain angle therebetween.
Namely, when planting the implant root into the alveolar bone, it may be necessary to avoid an anatomical structure(cortex which forms a lower alveolar pipe, biperforate, and maxillary sinus) of a maxilla or mandible under a certain circumstance. In order to avoid the above anatomical structure, an implant root bent at a certain angle is necessary. However, since the conventional implant root has a well in the center of the same, it is impossible to form a bent type implant.